Method of excavation



Feb. 15, 1955 w. M. HOMER 2,

METHOD OF EXCAVATION Filed Aug. 10, 1951 2 Sheets-Sheet l 7 WILLIAM M. HURNER,

. INVENTOR.

1955 w. NLHORNER 2,702,160

METHOD OF EXCAVATION Filed Aug. 10. 1951 2 Sheets-Sheet 2 WILL/AM M. HOMER INVENTOR.

United States Patent METHOD OF EXCAVATION William M. Homer, Houston, Tex.

Application August 10, 1951, Serial No. 241,204

2 Claims. (Cl. 2551.8)

This invention relates to a method of excavation which includes progressively advancing and retracting a drill stem having an open type reamer thereon into a bored hole, and the successive injection of water under pressure and then a fluid under pressure into the successive spaces provided by retraction, whereby the fluid under pressure acts to eject the formation cuttings from the bored hole as such ejection is abetted by the water which has earlier been injected outwardly of the fluid.

It is an object of this invention to provide a method of excavation including the drilling of a bored hole with a drill stem having an open type reamer afl'ixed thereto and in such method the drill stem is first rotated and advanced, and then rotated in retraction to compact the cutting outwardly thereof, then advanced inwardly and through water in the space provided by retraction, and then further advanced in drilling; then the drill stem is again retracted in rotation to further compact another mass of cuttings therebehind, and a compressed fluid is then injected into the inner space to force the cutting masses outwardly abetted by the water which has previously been injected.

It is also an object of this invention to provide a method of this class in which the water injected into the water filled space serves also to tend to seal against the outward escape of the compressed fluid employed, as air.

It is a further object of this invention to provide a method which employs an inexpensive fluid, as water, and an even less expensive fluid, as compressed air, to excavate a bore, whereby excavation is accomplished without withdrawing the drill stem from the bore, and without the use of an excavation plug or disc.

It is still a further object of this invention to provide a method of this class which is especially adapted for the excavation of horizontally extending bores.

It is yet a further object of this invention to provide a method of this class which is adapted for the excavation of bores which extend vertically or at angles to the horizontal.

Other and further objects will be apparent when the specification is considered in connection with the drawings in which:

Fig. 1 is a sectional elevation showing the first step in horizontal excavation and which shows a typical excavation machine;

Fig. 2 is a sectional elevation showing the second step in horizontal excavation;

Fig. 3 is a sectional elevation showing the third step in horizontal excavation;

Fig. 4 is a sectional elevation showing the fourth step in horizontal excavation;

Fig. 5 is a sectional elevation showing the fifth step in horizontal excavation; and

Fig. 6 is a sectional elevation showing the fourth step in vertical excavation.

Fig. 7 is a side elevation of a reamer of the type indicated broadly in Figs. 1-5, inclusive, taken along line 77 of Fig. 8.

Fig. 8 is an end view, taken along line 8--8 of Fig. 7.

l-leretofore, in one method of drilling bores and excavating cuttings therefrom, it has been necessary to drill a pilot hole through to the far side of a hummock, or elevated terrain portion. as a road bed. and then attach a reamer or cutter to ream the bore, after which a plug is pulled through to remove the formation cuttings. The step of pulling the plug often has to be repeated several times with much resultant delay. Also the terrific pres- 'wells, as oil wells, it is necessary to circulate the fluid down the drill stem to wash the formation cuttings upwardly in the casing annulus to the top of the well.

This invention is strictly a method invention and sets out to eliminate excavation problems hereinbefore encountered by using first water and then a compressed fluid, as compressed air, to force the formation cuttings out of the bore while requiring a minimum axial movement of the drill stern.

Fig. 1 shows diagrammatically one machine adapted to carry out such method, but it is herein pointed out that a. number of machines and devices can fulfill the same function. Such a machine 1 has a frame 2 which supports racks 3. The engine 4 is mounted on a guide base, not shown, which is adapted to slide along the racks 3. The engine 4 is connected to rotate the drill stem 5, and the steady rest 6 on the frame 2 supports the drill stem 5 at the end 7 0f the frame, while the bearing member 8, also mounted on the frame, supports the drill stem centrally of the frame.

Water is supplied to the drill stem bore by means of the hose 9 and swivel 10 and compressed air may enter the engine 4 by way of the air hose 11 and pass through the hollow drive Kelly 12 to the drill stem 5 connected thereto.

Pinions 14 on the shaft 15 mesh with the racks 3 and the shaft 15 is journalled in a bearing member, not shown, which is rigidly connected to the engine 4. The handle 16 is adapted to be reniovably connected to the shaft 15 or to a pinion 14 so that the engine 4 may be moved along the racks 3 as the drill stem rotates to ream the bore 18 by rotating its affixed cutter or reamer 17 of the conventional type having openings between its radial supports or spokes through which the cuttings are directed outwardly the bore 18. In the view of Fig. l a pilot bore 19 has previously been drilled, and the guide 20 is connected to the drill stem ahead of the reamer 17 and moves in the pilot bore.

Figs. 7 and 8 show one form of cutter or reamer for carrying out the functions of this invention. Such form is not all inclusive, and other constructions of reamers are applicable as well, and this invention is submitted to encompass a variety of such reamers. In the conventional disclosure shown, the rim 42 of the reamer 17 is supported from the drill stem 5, by means of spokes, arms, or radial support bars 49, which rigidly connect the rim and drill stem. Pipes 40 and 41 are included as part of the support bars 49, and are afiixed thereto, and extend from the drill stern 5, with which they establish inner fluid communication, radially outwardly to the rim. Blades 43 are connected to the arms 49, and each blade consists of a plurality of teeth 44. The blades 43 thus form rows extending from the drill stem 5 to the rim 42, and are topped by a tooth 45 at the rim, so that the tooth 45 overextends the other teeth 44 of each blade, as shown in Fig. 7. The pipes 40 and 41 have orifices 46 therein so that fluid may be pumped down the drill stem to pass outwardly through such orifices 46 for purposes to be hereinbelow described.

This invention is directed strictly to a method of excavation, consequently any type of machine will serve which has the following characteristics. The machine must have a hollow drill stem; must be movable in a direction axially of the drill stem; must be able to rotate the drill stem; and water or air, or broadly a liquid and a fluid, must be furnished to pass down the drill stem bore and out through the cutter or reamer thereon. As there are many types of devices that can carry out these requirements, the machine hereinabove described is stated to be only one of the wide variety of structures which may carry out the method of this invention.

In operation, the machine is actuated to ream for a distance of about three feet. Then a liquid, as water, is supplied into the drill stern bore, after, or as, the drill stem is withdrawn outwardly for a short distance, as shown in Fig. 2, to supply the space 25 into which the water is injected. When the drill stem is drawn outwardly to provide this space 25, rotation of the drill stem is continued in the direction of drilling, with the result that the mass of formation cuttings 26 is substantially compacted behind the cutter or reamer since the inclination or pitch of the rear end or edge of the reamer teeth 44 is such as to tend to direct the cuttings outwardly when the reamer 17 rotates as indicated by the arrow in Pi 8.

%V[eanwhile the water passes out through the orifices 46 in forced volume, to fill the space 25, and being .under pressure, part of the water will obviously enter into the surrounding formation and into the compact mass of cuttings 26 behind or outwardly of the space 25. it is also obvious that part of this water will pass into the surface separating the mass 26 from the surrounding formation.

As shown in Fig. 3, the drill stem and reamer are then advanced through the space 25 and drilling has been continued for another distance of say three feet. In point of time, this drilling ahead an additional distance is calculated to be accomplished before there can be any substantial dissipation of the water in space 25 either into the mass 26, into the surrounding formation. or into the new cuttings 27. Then, as shown in Fig. 4, the drill stem is again withdrawn a short distance as rotation continues in the direction of drilling with the result that a second mass of formation cuttings 27 is compacted behind the reamer or cutter. This exertion of force against the mass 27 also exerts pressure on the water remaining in the space 25 and forces such water into such masses 26 and 27 as well as along the periphery 28 of the mass 27 and along the periphery 29 of the mass 26, and also along the drill stem periphery portion 30 within the mass 26, and the drill stem periphery portion 31 within the mass 27.

As the second mass 27 has been compacted by the withdrawal of the reamer for a short distance, such withdrawal has provided the space 32. The water supplying means is now disconnected from the machine, and a fluid, as compressed air, is supplied through the machine and drill stem bore and forced into the space 32. After this the fluid, under pressure, must exert force on the mass 27 to move it outwardly. In this outward motion it must further press upon any water in the space 25, and takes up this space as it moves outwardly into contact with the mass 26. The water must consequently be forced into the masses 26 and 27 to a greater degree to thereby oppose the outward escape of the compressed fluid, as air. Also, the water must pass between the formation and the peripheral surfaces of the masses 26 and 27, so that it acts as a lubricant along such surfaces, as well as along the surface of the drill stem. and thereby this effect abets the fluid pressure in enabling it to more easily force the masses 26 and 27 from the Well bore, as shown in Fig. 5.

The boring method is not regularly used in sandy subsoil, which would cave in unless supported. For such sandy soil, the more conventional tunneling is followed. For boring and reaming work on clay subsoils the operation is begun with the reamer, and after an initial few feet of travel the further advance of the reamer is temporarily discontinued and the reamer is retracted. During reamer advance and to assist cutting action, water is fed in suflicient quantity to the cutting area for softening the clay being cut and for lubrication to minimize wear. The water wets the cuttings and the surrounding bore wall surface. The latter is troweled smooth and made more dense by the rotating wide peripheral rim or band of the reamer so that the clay surface of the bore becomes hard, smooth, and slick. The bore wall becomes a slippery slide surface. In addition to wetting the wall surface and the cuttings, the water fills the voids between the cuttings; and upon retraction of the reamer the mass of gooey and mucky cuttings is compacted and merged or molded into a solid cylindrical core filling the bore and being slidable on the slick cylindrical surface of the bore. If the reamer is fully retracted, the compacted cylinder unit will be completely ejected as a solid, plug-like mass to be broken up and manually shoveled to one side.

Instead of complete retraction, the reamer is usually brought back (see Fig. 2) only far enough to insure sufiicient compaction and molding f the cuttings, particularly at their inner face, and to only partially project the core avoareo from the bore. This initial retraction molds the clay into a unit with no tendency to bond it to the slick bore wall surface, and the additional cutting can proceed with minimum delay. The water tends to swell the compacted cylinder into a close sliding fit with the bore wall, and also to swell the surface around the pilot 20, and thus seals against excess leakage of compressed air which may now be introduced at the front of the retracted reamer. Air under relatively light pressure pushes the slippery, solid plug outwardly. In practice it is not necessary that the plug be blown entirely out of the bore at one time, and especially in the initial stages. The bore can be cleaned out in steps of reamer advance and retraction. Thus if the first push-out terminates with the mass 26 partially ejected, as seen in Fig. 3, the following advance of the reamer leaves the space 25, and as the new clay cuttings are massed behind the reamer, and since the end face of the first core was solidly compacted, as was the bore wall surface by reason of the troweling band of the reamer. these wetted and packed faces are somewhat resistant to quick soaking of a further copious water supply, and the water supply backs up in the space 25 and at the same time is taken up by the new cuttings and the newly reamed bore wall surface. Excess water cannot readily escape, but it tends to form a more or less solid force-transmitting body in so far as it is not absorbed by the hard clay. Now, after the second increment of reaming, the reamer is again retracted to compact the second mass of cuttings, with the compactions beginning at the front end and moving on back until the mass is molded into the slidable cylinder or core. When pressure air acts against its forward solid face, it is displaced bodily rearwardly as a unit. Its sliding travel is transmitted to the first core. either directly or through any water trapped within the intervening space. The blowout can continue to completion or only partially, as the working crew desires. Fig. 5 illustrates the relation of the second plug still partly in the bore after the first plug has been completely ejected.

These steps are repeated until the hole reaches completion, but just before the final reaming operation it is customary to fully blow out all previously cut and compacted cores. Because of the slippery slide surfaces and the relatively close fit, high pressure air is not needed to blow out the plugs, and they are ejected easily with no danger of blowing up the embankment.

The theory of this invention can also be applied to vertical excavation as shown in Fig. 6 in which a drill stem 35 has the drilling bit 36 thereon that drills a vertical bore 37. In this type of excavation, conventional vertical drilling equipment can be employed, as the rotary rigs used in oil well, water well, or core drilling, it only being necessary that the rotatable drill stem can be moved axially, and that a liquid having lubricating properties, and later a fluid under pressure, can be supplied down the drill stem bore to pass outwardly below, and through the reamer or cutter. Such pressurized fluid will obviously force the mass 38 against the liquid pocket 39, and will finally force both the mass 38 and 39 upwardly against gravity, and out of the well bore 37.

As regards the reamer or cutter employed, although no transverse view is shown, it is pointed out that the connection hub of such reamer or cutter must be connected to the rim thereof by means such as spokes leaving clearance thereinbetween to permit the liquid or fluid to pass therethrough.

Broadly this invention considers a method of excavation which provides lubricant pocket means between masses of formation cuttings and which then provides a fluid under pressure inwardly thereof to force the masses outwardly of the bore.

What is claimed is:

l. A method of earth excavation comprising the steps of, drilling a pilot bore, reaming the pilot bore with an open type reamer for a distance, continuing rotation of the drill stern in the direction of reaming while withdrawing the drill stem outwardly to compact a mass of formation cuttings behind the reamer, injecting water through the drill stem and reamer into the space provided inwardly of the withdrawn reamer, advancing the reamer through the space and continuing reaming for another distance, continuing rotation of the drill stem in the direction of reaming while withdrawing the drill stem outwardly to compact another mass of formation cuttings behind the reamer, and injecting compressed air through the drill t 6 stem and reamer into the space inwardly of the reenter against the inner compacted mass and move the masses to force against the inner compacted mass an move the outwardly. masses outwardly. d A mgthodfof exgavation cotrlnprising the steps of, 5 References Cited in the file of this patent ri ing a ore or a 'istancc wit an open type cutter, withdrawing the drill stem outwardly to compact a mass UNITED STATES PATENTS of formation cuttings behind the cutter; injecting water 1,346,939 Carmichael July 20, 1920 through the drill stem and cutter into the space provided 2,122,099 Jeffrey June 28, 1938 inwardly of the withdrawn cutter, advancing the cutter 2,126,576 Ranney Aug. 9, 1938 through the space and continuing drilling for another dis- 10 2,234,451 Ransome Mar. 11, 1941 tance, withdrawing the drill stem outwardly and to com- 2,514,585 Natland July 11, 1950 pact another mass of formation cuttings behind the cut- 2,664,273 Merrick Dec. 29, 1953 ter, and injecting compressed air through the drill stern 2,693,345 Martin et a1 Nov. 2, 1954 and cutter into the space inwardly of the cutter to force 

